1. Field
The present disclosure relates to a fuel cell.
2. Description of the Related Art
In general, a solid polymer electrolyte fuel cell includes a solid polymer electrolyte membrane, which is made from a solid polymer ion-exchange membrane. The fuel cell includes a membrane electrode assembly (MEA), which includes a solid polymer electrolyte membrane and an anode electrode and a cathode electrode sandwiching the solid polymer electrolyte membrane therebetween. Each of the cathode electrode and the anode electrode includes a catalyst layer (electrode catalyst layer) and a gas diffusion layer (porous carbon). The fuel cell further includes a pair of separators (bipolar plates) sandwiching the MEA therebetween. A predetermined number of such fuel cells are stacked and used, for example, as a vehicle fuel cell stack, which is mounted in a fuel cell vehicle.
In order to prevent gas leak or the like, it is necessary that a fuel gas and an oxidant gas be gas-tightly sealed in a fuel cell. Moreover, in order to maintain a cooling function, it is necessary that a coolant be liquid-tightly sealed in the fuel cell. Therefore, various sealing structures are used in fuel cells.
For example, Japanese Patent No. 4733915 describes a fuel cell that includes a membrane electrode assembly including an electrolyte membrane and a first electrode and a second electrode sandwiching the electrolyte membrane therebetween. The second electrode has a surface area greater than that of the first electrode. The membrane electrode assembly and first and second separators, sandwiching the membrane electrode assembly therebetween, constitute a power generation cell.
First and second sealing members are respectively disposed on the first and second separators. An inner seal and an outer seal are formed on one of surfaces of the second sealing member facing the first electrode. The inner seal is disposed between the electrolyte membrane and the second separator, and the outer seal is disposed between the first and second separators.
A coolant seal is formed on the other surface of the second sealing member, which is opposite to the one of the surfaces, or on one of surfaces of the first sealing member that is opposite to the other surface facing the second electrode. The coolant seal is disposed so as to correspond to the outer seal and so as to seal a coolant channel. The inner seal, the outer seal, and the coolant seal are configured so that they can receive substantially the same sealing linear pressure in the stacking direction against a load applied in the stacking direction.